Antwort, 14.05.2009 21:11 von The Bartman
Hi Def_leppard,
The sail should look the same, no matter if you use RDM or SDM. The required length of the extension is normally indicated on the sail. Take the indicated luff length minus 430 and you've got the length you need to set your extension to. Normally this leaves a gap of a few cm between sail and mast foot, even when the downhaul is fully pulled out to maximum tension.
Be aware that extensions are often 30 cm, while some sails may require more than 30 cm extension. My own NP Search 6.2 requires 430 + 37 cm for example. This might be the case in your situation. If the mast + extension is too short, this may also explain the contact of sail and boom: more luff tension will give the sail a flatter profile.
Good luck with tuning
The Bartman